1. Technical Field
The present invention relates to a light control device for controlling transmission amount of light emitted from a predetermined emission area, and a lighting device and a projector including the light control device.
2. Related Art
Currently, such type of projector is known which includes a light source device, a light modulation device for modulating light emitted from the light source device according to image information to produce image light, and a projection device for enlarging and projecting the produced image light. The light source device included in the projector in most cases has a light source lamp, and a reflection mirror for reflecting light emitted from the light source lamp to release the light in one direction.
As an example of this type of projector, such a projector has been proposed which has a light control device for controlling the amount of light emitted from the light source device and entering the light modulation device for the purpose of improvement in the contrast of projected images or other purposes (see JP-A-2007-71913, for example).
The light control device shown in JP-A-2007-71913 includes a pair of shielding members disposed symmetric with respect to the center axis of entering light, a pair of rotation shafts for supporting the shielding members and rotating to interpose the shielding members on the optical path of the light, a drive mechanism for rotating the pair of rotation shafts, and a fixing member for supporting the pair of the rotation shafts and the drive mechanism as one piece. This light control device is disposed between a pair of lens arrays provided to uniformly illuminate an image forming area of a liquid crystal panel as light modulation device with the light emitted from the light source device. The shielding members are inserted into the light transmitting area of the light control device according to the drive of the drive mechanism, that is, the rotation of the rotation shafts so as to control the amount of light supplied to the image forming area by partially shielding the supplied light using the shielding members.
According to the light control device disclosed in JP-A-2007-71913, the shielding members are disposed orthogonal to the center axis of the light supplied to the shielding members when the pair of the shielding members are full close, that is, when the pair of the shielding members are positioned on the same flat plane. In this case, the light supplied to the shielding members travels along the optical path of the light emitted from the light source device and supplied to the shielding members in the opposite direction and reaches the light source device. When the light reflected by the shielding members enters the light source device (particularly the light source lamp) in this manner, the temperature of the light source device increases. As a result, the light source device easily deteriorates.